[QT]简易画板的实现

void MainWindow::Painter()
{
    QPainter painter;
    QImage image(500,500,QImage::Format_ARGB32);
    painter.begin(&image);
    painter.drawLine(QPoint(0,0),QPoint(100,100));
    QPen pen(Qt::green,5,Qt::DotLine,Qt::RoundCap,Qt::RoundJoin);
    painter.setPen(pen);
    QRect rectangle(70.0,40.0,80.0,60.0);
    int startAngle=30*16;
    int spanAngle=120*16;
    painter.drawArc(rectangle,startAngle,spanAngle);
    painter.end();
    ui->label->setPixmap(QPixmap::fromImage(image));

}